Arguments around the best cartridge for whitetail deer generally focus on things like the best deer hunting caliber, or bullet weight, velocity, and energy. Ballistically, the 25 Creedmoor is the best cartridge in the Creedmoor family because with Creedmoor cartridge case capacities, and the pressures Creedmoor cartridges are loaded to, a 0.257-caliber bullet provides optimum performance. Thers’s only one magnum cartridge on this list because you don’t need a magnum cartridge to kill a deer, whether it’s a big deer or a little deer.